At the present time, silicon is the semiconductor of choice for the fabrication of most semiconductor devices including, but not limited to, microprocessors and random access memories (RAM's). The use of silicon, however, severely limits the parameters which can be used in the design of such devices. When using silicon, for example, one is limited to a band gap of 1.1 electron volts. The p-n junction profiles are limited to the graded junction produced by diffusion and the step junction produced by epitaxy. Since methods are not available for varying the band gap of silicon or for obtaining junction profiles other than graded or step, device design engineers have had no incentive to consider other possibilities for their designs. A further limitation of the use of silicon is a need for metalization to make low resistance ohmic contacts for the various regions of the devices.
Non-metallic conductive polymers and other materials are, of course, known to the art. For example, it is well known that graphite is a very good conductor in the plane of the .pi.-bonded carbon atoms. It is conduction between the planes of graphite which is not very good. The distance between adjacent carbon atoms in the plane is 1.42 .ANG., whereas the distance between the planes is 3.41 .ANG.. The distance between adjacent carbon atoms in benzene is 1.39 .ANG., for which the value of the overlap integral for carbon 2p.sub.z -orbitals (the z-axis is perpendicular to the plane) is about 0.25. Since each carbon atom in graphite has two 2p.sub.z -orbitals (differing only by their spin quantum numbers) and only one electrode available for them, conductivity is possible for graphite within the plane. However, a graphite-like system is not satisfactory for the fabrication of semiconductor devices since it is only a 2-dimensional conductor. Linear conducting polymers are also known but, since they only conduct linearly, they are also not well suited for semiconductor devices or for many other uses wherein various types of conductive devices are needed.
It would be highly desirable to provide a new type of conductive polymer which would allow a great reduction in the design limitations which presently face device design engineers. It would also be desirable to provide the engineers with a means of varying the band gap of the semiconducting or metallic conducting material at will. It would still further be advantageous to provide the design engineer with means to vary controllably conductivity and conductivity type (p-type, n-type or metallic) at will. It would be still further advantageous to provide the design engineer with means of controllably producing various different types of junction profiles. Still further, it would be desirable to provide the design engineer with a means of producing metallic regions within a device as well as on its surface.